JPH04325142A - Magnetoresonance imaging device - Google Patents

Abstract

PURPOSE:To photograph a testee body with the magnetoresonance imaging device without compelling the testee body to an unnatural posture. CONSTITUTION:A head rest 7 is supported via a moving shaft 14 having a square shape to a supporting part 10. The end 14a of the moving shaft is supported slidably in a long hole 15 of guide parts 13, 13. A piston mechanism part 12 is constituted of a cylinder part 17 and a piston part 18. An always specified pressure (about half the average weight of the head of an adult) is held applied on the inside of the cylinder. The front ends of lock screws 16 are joined to ends 14a of the moving shaft through the long hole 15 of the guide part 13. The head rest 7 moves vertically and can be fixed to a desired position when the lock screws 16 are loosened. The head rest is properly matched with the desired position according to the physical shape even if a large-diameter coil for covering the entire area of the testee body is not used in this way; in addition, the tight contact of a high-frequency coil for signal reception and the testee body is possible and, therefore, the S/N of the reconstituted tomographic image is improved and there is an effect of decreasing motion archifact.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION The present invention relates to a magnetic resonance imaging apparatus that uses magnetic resonance phenomena to obtain a tomographic image of a desired part of a subject, and particularly relates to an improvement of a bed having a head rest equipped with a receiving high-frequency coil. It is something.

0002

2. Description of the Related Art In a conventional magnetic resonance imaging apparatus, a gradient magnetic field generating coil and a transmitting high frequency coil are provided in a gantry constituting a static magnetic field generating apparatus. Further, a bed used in a magnetic resonance imaging apparatus has a table on top of which a subject is placed, and a head holder at the tip of the table. The head support supports the head of the subject and is provided with a receiving high frequency coil. The receiving high-frequency coil applies a uniform static magnetic field to the subject in the gantry, and when the transmitting high-frequency coil applies electromagnetic waves at a frequency that excites magnetic resonance to the subject, the magnetic resonance generated from the subject is detected. It receives signals and has a ring shape that covers the head of the subject to be examined.

[0003] At that time, in order to identify the magnetic resonance signal from the subject during the examination, a gradient magnetic field is applied in an appropriate direction by the gradient magnetic field coil, and a cross section of the examination site at an arbitrary angle is obtained depending on the direction of the gradient magnetic field. That's what I do. Therefore, the head rest is generally fixed to the top end of the table parallel to the horizontal plane.

0004

[Problems to be Solved by the Invention] The above-mentioned prior art does not take into account cases in which images are taken not only of subjects who originally have a physical disability, but also of subjects who have a disability at the time of the examination. For example, when trying to photograph a subject whose neck is not bent or whose back is bent,
In the conventional technique, when a subject is laid down on a bed and the head is supported by a head support in a state parallel to a horizontal plane, the chin of the head moves up and down. Therefore, as described above, since the receiving high-frequency coil is fixed to the head holder in a horizontal plane, it may not be possible to take pictures as it is.

[0005] Therefore, the receiving high-frequency coil is replaced with a receiving high-frequency coil having a larger diameter so that the subject's jaw does not get stuck. However, when a receiving high-frequency coil with a large diameter is used, a gap is created between the coil and the examination site of the head, resulting in a problem that the S/N ratio of the tomographic image decreases. In order to improve the S/N ratio, it is preferable to bring the region to be imaged and the receiving high-frequency coil into close contact, but the current situation is that even if there is a gap, the image is still being taken.

[0006] Furthermore, the subject must take a posture that matches the head holder, and if the subject is photographed in an unreasonable posture, he or she will be forced to suffer pain. Therefore, if the camera is photographed in an unreasonable position, the camera will move during the recording, causing problems such as motion artifacts.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a magnetic resonance imaging apparatus that enables imaging even of a handicapped subject without causing pain or forcing the subject into an unreasonable posture. Our goal is to provide the following.

[0008]

[Means for Solving the Problems] In order to achieve the above object, there are provided a static magnetic field generating means for applying a static magnetic field to a subject, a gradient magnetic field generating means for applying a gradient magnetic field to the subject, and a biological tissue of the subject. It has a headrest equipped with a transmitting high-frequency coil that irradiates high-frequency waves to excite magnetic resonance in the nuclei of the atoms that constitute the atom, and a receiving high-frequency coil that detects the echo signal emitted by the magnetic resonance. , a magnetic resonance imaging apparatus comprising a bed on which the subject can be placed, including means for moving the head support in parallel in a direction perpendicular to the bed.

[0009]

[Operation] In the present invention, the head support of the bed is configured to be able to move in parallel in the vertical direction by the moving means, so in the case of a subject whose neck is not bent or whose back is curved, The head support can be appropriately adjusted to a desired position depending on the posture of the subject. Therefore, the subject's chin or the like will not get stuck in the receiving high-frequency coil, and there will be no need to replace the receiving high-frequency coil with a larger diameter receiving high-frequency coil. Moreover, since there is no need to use a large-diameter receiving high-frequency coil, the subject can be brought into close contact with the receiving high-frequency coil that is pre-installed on the bed, and there are no gaps, making it possible to reconstruct images. S/N of tomographic image
This not only prevents the ratio from decreasing, but also allows the subject to be stably supported on the head support, which prevents the subject from moving during imaging and prevents motion artifacts from occurring.

0010

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to FIGS. 1 to 10. FIG. 1 is a cutaway perspective view of essential parts of a bed showing a first embodiment of a magnetic resonance imaging apparatus according to the present invention, FIG. 2 is a perspective view of a head holder, FIG. 3 is a side view of the head holder, and FIG. FIG. 5 is a partial cross-sectional view taken along line A-A of FIG. 5, and FIG. 5 is an explanatory perspective view showing the magnetic resonance imaging apparatus.

In FIG. 5, 1 is a static magnetic field generator, 2 is a bed, 3 is an MRI unit, 4 is a central processing unit,
5 is a multi-format camera. Although the static magnetic field generator 1 is not shown in detail, it includes a static magnetic field generating magnet for generating a uniform static magnetic field, a gradient magnetic field coil provided in the internal space of the magnet for generating a gradient magnetic field, and a gradient magnetic field coil for generating a gradient magnetic field. A transmitting high-frequency coil is provided inside the gradient magnetic field coil to irradiate the subject with high-frequency waves for exciting magnetic resonance.

[0012] The bed 2 is for resting the subject, and has a head holder 7 at the tip of a table 6 on the top thereof. The head support 7 supports the head of the subject, and as shown in FIGS. 1 and 5, a receiving high-frequency coil 8 is provided so as to be movable in parallel to a horizontal plane by a guide portion. The receiving high-frequency coil 8 is for receiving magnetic resonance signals from the subject during imaging, and has a ring shape. As shown in FIG. 1, the guide portion includes a guide rail 71 fixed to the back surface of the head holder 7 so as to extend substantially horizontally.
and a guide rail 81 that is fixed to the receiving high-frequency coil 8 and fits on both sides of the guide rail 71,
By moving the guide rail 81 along the guide rail 71, the receiving high-frequency coil 8 is moved in the horizontal direction, that is, in the body axis direction, as shown by the arrow. The MRI unit 3 houses a high-frequency power source for applying high-frequency pulses to a transmitting high-frequency coil, a power source for gradient magnetic field coils, and the like. The central processing unit 4 houses an image processing section and a sequencer therein. The multi-format camera 5 photographs MR images on film.

[0013] This magnetic resonance imaging apparatus moves the table 6 above the bed 2 on which the subject is placed into the static magnetic field generating device 1, thereby applying uniform static to the subject using the static magnetic field generating magnet. When a magnetic field is applied and a high-frequency pulse amplified by the high-frequency amplifier in the MRI unit 3 is applied to the transmitting high-frequency coil in the static magnetic field generator 1, the transmitting high-frequency coil emits electromagnetic waves that excite magnetic resonance signals in the subject. irradiated. After a certain period of time after irradiation, the receiving high-frequency coil 8 detects a magnetic resonance signal from the subject, the detected signal is amplified by the amplifier in the MRI unit 3, and after it is detected, it is converted into a digital signal by the A/D converter. and sent to the image processing section of the central processing unit 4. The image processing unit performs processing such as Fourier transform to reconstruct an image. that time,
Multi-format camera 5 captures the reconstructed image on film.

In this embodiment, the bed 2
It has means for vertically moving the head support 7 in parallel. The moving means includes a head support 7 as shown in FIGS. 2, 3 and 4.
The head support 7 is provided with a piston support portion 11, and the support portion 10 is provided with a piston mechanism portion 12 and a guide portion 13. Specifically, a rectangular moving shaft 14 is formed to fit on the base of the head holder 7, and end portions 14a protrude from both ends of the base of the head holder 7. The end portions 14a are supported by the guide portions 13, 13, respectively. This guide part 13 is connected to the moving axis 1 as shown in FIG.
An elongated insertion hole 15 for inserting the end portion 14a of 4 is provided in the vertical direction. Furthermore, the piston mechanism section 12 is composed of a cylinder section 17 and a piston section 18, and a constant pressure (approximately 2/2 the average weight of an adult's head) is always applied inside the cylinder. Reduces the movement power of On the other hand, the tip of the fixing screw 16 passes through the elongated hole 15 of the guide part 13 and is screwed into the head holder 7. When the fixing screw 16 is loosened and the head support 7 is moved in parallel in the vertical direction, the fixing screw 16 follows the movement and the guide portion 1
3 and tightens the head holder 7 against the guide portion 13, the head holder 7 can be fixed at a desired position in the vertical direction. Therefore, screw holes (not shown) into which fixing screws 16 are screwed are provided on both end surfaces of the moving shaft 14 at the base of the head support 7. Note that the guide section 13 is attached to the support section 10 with screws or the like, and the support section 10 is attached to the table 6 as shown in FIG.

In the magnetic resonance imaging apparatus configured as described above, a subject is placed on a bed 2 during an examination. At this time, in the case of a subject whose neck is not bent or whose back is bent, the horizontal position of the head holder 7 is changed by the moving means according to the body shape of the subject. That is, when the fixing screw 16 is loosened, the head holder 7 moves upward due to the pressure inside the cylinder, and then the head is placed on the head holder 7 and the fixing screw 16 is tightened at a desired position to fix the head holder 7. Thereby, the head of the subject can be stably supported and fixed on the head holder 7, and the head can be easily positioned.

In this way, by moving the head support 7 in parallel in the vertical direction, it can be adjusted appropriately according to the body shape of the subject. Therefore, it is no longer necessary to replace the receiving high frequency coil 8 with a larger diameter receiving high frequency coil 8. Moreover, since the receiving high-frequency coil 8 with a large diameter is not used, there is no gap between the receiving high-frequency coil 8, which is pre-installed on the bed 2, and the subject. This not only prevents the S/N ratio of increasing tomography from decreasing, but also prevents the subject from moving during imaging, thereby preventing motion artifacts from occurring.

FIGS. 6, 7 and 8 show other embodiments of the magnetic resonance imaging apparatus of the present invention. In this case, the moving means includes a head rest 7a and a support part 2, as shown in FIG.
0 is integrally formed via a parallel displacement adjustment screw 21, and the head holder 7a is provided with a screw hole 22 and a parallel displacement pin 23 for inserting the parallel displacement adjustment screw 21, and the support portion 2
0 is provided with a screw hole 24 for inserting a parallel movement adjustment screw 21 and a guide hole 25 for parallel movement.

The parallel movement adjustment screw 21 is for adjusting the amount of movement when parallel movement is made in the vertical direction.
It has threaded parts above and below a. The screw portion is connected to the head holder 7.
If the side to be inserted into a is a right-handed screw, the side to be inserted into the support portion 20 is a left-handed screw. In other words, when the knob portion 21a is turned in one direction, the head support 7a and the support portion 20 move in the opposite direction. The parallel movement pin 23 is provided on the head support 7a side to prevent the head holder 7a from rotating in the same direction as the direction in which the knob 21a is turned when the knob 21a is turned and moved in parallel. ing. The guide hole 25 for parallel movement is a hole for guiding the pin 23 for parallel movement, and is provided in the support portion 20 . Note that the support part 20
is attached to the table 6 as shown in FIG.

According to this embodiment, since the head support 7a can be moved in parallel in the vertical direction, basically the same effect as the first embodiment can be obtained.

FIGS. 9 and 10 show another embodiment of the magnetic resonance imaging apparatus according to the present invention. The movement adjustment method in this case is to insert a spacer 30 as shown in FIG. 10 into the lower part of the head holder 7b and position it at a desired position in the vertical direction. Note that several types of spacers 30 with different thicknesses t are prepared. Since the head holder 7b is attached to the table 6 with fixing screws 31, a notch 32 is provided in the spacer 30 so that it can be easily moved. According to this embodiment, the configuration of the moving means can be simplified compared to the first and second embodiments.

[0021]

As described above, according to the present invention, the head support of the bed can be moved horizontally in the vertical direction by the moving means, and can be used to examine subjects who cannot bend their necks or whose backs are curved. In the case of an examiner, etc., the head holder can be adjusted to the desired position according to the patient's posture, so the patient's chin does not get stuck in the receiving high-frequency coil, and a large It is no longer necessary to replace the receiving high-frequency coil with a larger diameter receiving high-frequency coil, and the receiving high-frequency coil and the subject can be brought into close contact, which reduces the S/N ratio of tomographic images when reconstructing images. This has the effect of not only preventing this, but also preventing motion artifacts from occurring.

[Brief explanation of drawings]

FIG. 1 is a cutaway perspective view of the main parts of a bed showing a first embodiment of a magnetic resonance imaging device.

[Figure 2] Perspective view of head holder

[Figure 3] Side view of head holder

[Figure 4] Local sectional view taken along line A-A in Figure 2

[Fig. 5] Explanatory perspective view showing a magnetic resonance imaging device

FIG. 6 is a perspective view of a head support showing a second embodiment of the magnetic resonance imaging device.

[Fig. 7] Local sectional view taken along line B-B in Fig. 6

[Figure 8] Figure 6
Local sectional view along line C-C of

FIG. 9 is a perspective view of a head support showing a third embodiment of the magnetic resonance imaging device.

[Figure 10] Perspective view of spacer

[Explanation of symbols]

1 Static magnetic field generator 2 Bed 6 Table 7 Head holder 7a Head holder 7b head holder 8 High frequency coil for reception 10-18 Transportation means 20-25 Transportation means 30-32 Transportation means

Claims (1)

[Claims] 1. Static magnetic field generating means for applying a static magnetic field to a subject, gradient magnetic field generating means for applying a gradient magnetic field to the subject, and exciting magnetic resonance in the nuclei of atoms constituting biological tissue of the subject. a bed on which the subject can be placed; 1. A magnetic resonance imaging apparatus comprising: means for moving the head support in parallel in a direction perpendicular to the bed.